Adhesion of nano-objects to chemically modified surfaces

• Main Author: Barker, Kane McKinney
• Published: Georgia Institute of Technology 2010
• Subjects: Tribology; Peeling; Adhesion; Dynamic force spectroscopy; Carbon nanotubes; Foce curve; Resonance frequency; Atomic force microcope; Force spectroscopy; Atomic force microscopy; Nanoelectromechanical systems
• Online Access: http://hdl.handle.net/1853/31837

The Atomic Force Microscope (AFM) is an instrument that is capable of measuring intermolecular forces between single molecules. Multi-Parameter Force Spectroscopy (MPFS) is a technique that uses the AFM. MPFS enables the acquisition of force curves and thermal resonance of the system under investigation. This technique can shed light on the mechanical behavior at the molecular level. Improvements described herein have enhanced the sensitivity of MPFS over background noise. This investigation focuses on the mechanical and interfacial properties of three carbon nanostructures: long nanotubes, nanocoils, and nanoloops. Different types of adhesion are encountered, measured and discussed: friction, rupture, and peeling. The elastic modulus of long carbon nanotubes is calculated from frequency shifts when the system is put into tension. An elastica model is applied to the post-buckled carbon nanotubes, which enables the estimation of the static coefficient of friction on chemically modified surfaces. The compression of a nanocoil at large contact angles reveals that changes in oscillation amplitude do not occur from damping, but from adding stiffness into the systems measured herein. This result is counter to the assumptions of dynamic force spectroscopy. Finally, carbon nanoloops are brought into and out of contact with several different surfaces. The force curve and frequency response of the system shows the difference between rupture and peeling. The results presented herein lead to a better understanding of the mechanical and tribological properties of the carbon nanostructures.